docs: def percentile(values, k):
      """Find the percentile of a list of values.
  
      :param list values: The list of values to find the percentile of
      :param int k: The percentile to find
      :rtype: float or int
  
      """
      if not values:
          return None
      values.sort()
      index = (len(values) * (float(k) / 100)) - 1
      return values[int(math.ceil(index))]